Fix for invalid matching symbol in vim keymap.

When the matching symbol of a closing bracket is on a different
line, it will match to the incorrect opening bracket. For example,
go to http://codemirror.net/demo/vim.html and place the cursor on
the closing brace at line 11 and press '%'.  It will incorrectly
match the opening brace on line 4 instead of the brace on line 8.
This patch fixes that by starting the line search at the *end* of
the line when searching backwards.
[manual] Small clarification
[vim keymap] Implement scroll actions like zz
[manual] Mention that the value option also accepts Docs
[manual] Fix broken anchor links
Fix b-tree visualization
Fix double-history-rebase bug in document sharing

Add test.
Remove stray conflict marker
Fix inconsistencies in operation nesting

Operating on line widgets from within an operation would cause
crashes.
Be more careful about redrawing widgets, fire a 'redraw' event on them

Issue #1164
[linter] Disallow trailing commas
Removed superfluous colon; IE compatibility issue.
[formatting demo] Extend selection when commenting a region

Closes #1176
tiddlwiki => tiddlywiki
Add "hide"/"unhide" events for markers

These fire when the marker is removed/resurrected by editing and undo
operations.

Closes #1093
Add show-hint add-on to replace simple-hint
[addon/xml-hint] Move to simple-hint and a saner interface
Fix bug in the way event handlers are called

Issue #1178